gregory



R. W. GREGORY.

OH. BREAK ELECTRIC SWITCH.

APPLICATION HLED NOV.3, 1911.

Patented Jan. 25, 1921.

3 SHEETS-SHEET I.

R. W. GREGORY.

01L BREAK ELECTRIC SWITCH.

APPLICATION FILED NOV. 3, 1917.

3 SHEETS-SHEET 2.

Patented Jan. 25, 1921.

R. W. GREGORY.

01L BREAK ELECTRIC SWITCH.

APPLICATION man NOV-3,1917.

Patented Jan. 25, 1921.

3 SHEETSSHEET 3- UNITE era @FFICE.

RICHARD WALTER GREGORY, OF NEW GASTLE-O1\T-TYNE, ENGLAND, ASSIGNOR T0 ELECTRICAL IMPROVEMENTS LIMX'LED, G1? NEW'CASTLEON-TYNE, ENGLAND,

OIL-BREAK ELECTRIC SWITCH.

Application filed November 3, 1917.

, To all whom it may concern 'oil,-so arranging that these vapors shall not come in contact with conductors of difierent potential within or close to the switching mechanism, so elongating and attenuating the are that its exposed surface shall be as large as possible with respect to its volume, utilizing the buoyancy of the hot vapor con stituting the are for this purpose, setting up a natural circulation of the oil so as to bring cool parts thereof to the arc, and pro ducing all these effects by the natural forces set up by the electric current broken at the switch.

This is accomplished according to this invention by so arranging the contact arms that the are produced between them is substantially horizontal, by providing a free vertical vent for the vapors and by so disposing the conductors through which the current passes to the contact arms that the electromagnetic forces tend to elongate the arc'and force it upward through the oil.

Further, a tubular screen formed of or lined'with insulating material is arranged to surround the contact arms to shield the conductors from contact with the products of the arc and to assist in the circulation of the oil caused by the arc vapors.

- In the accompanying drawings which illustrate diagrammatically three typical forms of oil-break switch accordingto this invention,

Figure 1 1s a vertical section showing the contact arms open.

Fig; 2 a similar vertical section showing the contact armsin their normal or closed position, and p Fig. '3 a plan section of a construction of the improved switchin which the contact arms and the conductors entering and leaving the switch are in the same vertical plane.

Specification of Letters Patent.

Patented Jan. 25, 1921.

Serial No. 200,141.

Fig. 4: is a figure showing the circulation of the cooling oil.

Fig. 5 is a view corresponding to Fig. 1, but of a form of switch in which the con tact arms and the conductors entering and leaving the switch are arranged in vertical planes at right angles to one another.

Fig. 6 is a vertical section at right angles to Fig. 5.

Fig. 7 is a sectional plan.

Fig. 8 is a vertical section of a construe tion embodying modifications of the screen and tank and of the contact arms.

Fig. 9 is a plan of the form of screen shown in Fig. 8 and of the contact arms. and I Fig. 10 shows, by way of example only, one construction of mechanism for opening and closing the contact arms.

With reference first to the construction represented in Figs. 1, 2 and 3. A is the oil tank containing oil up to say the level of the broken line B, and C is a vent of ample size leading to the. atmosphere or if desired out of the building in which the tank is situated. D, D and E, E are respectively the conductors by which current enters and leaves the switch. These conductors pass through the tank cover A by the insulating bushings F, F proceeding vertically through the oil and bending hori zontally at the points (Z, 6 toward the points 03, 6. Here they join the hinged or pivoted contact arms G, G. The circuit is broken by the parting of these arms which may be caused by any convenient mechanism such for example as is hereinafter described with reference to Fig. 10. The are produced on the breaking of the circuit has normally (when considered as uninfiuenced by the repelling forces hereinafter referred to) a substantially horizontal path between the ends of the arms G, G as shown by the dotted line 7. Between the vertical conductors D, E and the contact arms G, G and of such dimensions as to enable the said arms to move fully apart, an annular or tubular screen H of insulating material is arranged so as to be entirely immersed in the oil. The main object of this screen is to prevent the are products from coming into contact with the conductors D, E.

It will be seen that in the arrangement shown the buoyancy of the hot vapors pro duced by the arc causes them to rise upward through the oil so lengthening and increasing their cooling surface. This tendency is of use in assisting to break the circuit. It will also be seen that the direction of cur-- rent in the horizontal portions D and E of the entering and leaving conductors is opposite to that of the current in the are. An electromagnetic force is therefore produced which elongates the arc by repelling it upward as shown by the bow-shaped line 7. lVhen the are is thus bow-shaped the direction of the current in the bowed ends of the arc is the same as is the direction of the current in the adjacent vertical conductors D, E so that these bowed ends are attracted toward the said vertical conductors and the are thus still further elongated, see line 7. These repelling and attracting forces together with the buoyancy of the arc prod.- ucts produce. a great attenuation of the are so that it is more readily cooled by the oil than would otherwise be the case. These repelling and attracting forces being proportional to the current passing through the circuit are most beneficial when most required, that is tosay, when the switch is breaking heavy currents as for instance may occur when there is a breakdown of appa ratus supplied by the circuit.

It is to be noted that the screen H entirely surrounds the arc and that it is placed well above the bottom of the tank A and below the surface of the oil therein. A tree circulation of the oil is therefore able to take place as shown by the arrows in Fig. l. Vhen an arc is formed, the hot are vapors rise rapidly to the surface of the oil. Such portion of the oil as is heated by the arc passes upward within the screen and is placed by cool oil from the lower parts of the tank.

The form shown in Figs. 5. 6 and T differs from that already described in that the conductors D, E instead of being in the same vertical plane as the contact arms Gr, G are in a vertical plane at right angles thereto. In this form the arc is still repelled upward by the current in the horizontal portions D, E of the conductors as is shown by the bow-shaped broken lines f. 7" in Fig. At the same time the attracting forces of the current in the vertical portions D, E of the conductors attract the bowed ends of the are so as to give the latter a form which in plan resembles the letter S. This is clearly shown by the curve f in Fig. 7.

In Figs. 8 and 9 it will be seen that the screen H differs from that shown in the figures already described. Instead of being merely a hollow cylinder of insulating material it consists of such a cylinder acting as a liner to a hollow cylinder of metal H, a much stronger construction and one more capable of withstanding severe explosions being thus obtained. It will also be seen that in this case the vent C instead of springing from the tank cover or switch top A is an upward prolongation of the metal part II of the screen. As shown in Fig. 8 the insulating liner H extends somewhat below the lower part of the metal cylinder H so as the better to protect the conductors connected with the contact arms from the efiects of the arc. In the construction here illustrated the holes H serve to permit circulation of the oil as before.

Figs. 8 and 9 also illustrate an arrangement in which the contact arms G, G are crossed. This obviates the crossing or overlapping of the horizontal parts D, E, of the conductors connected with them. In this case the arms are made with lateral exten sions G G at their heads or free ends so as to shut or lock against one another. The contact arms may be insulated except at the contacting parts.

In Figs. 1 to 9 which are merely diagrammatic no mechanism is shown for opening and closing the contact arms G, ,T but it is to be understood that any suitable arrangement may be employed.

By way of example only Fig. ll) shows a. mechanism which may be used for the purpose. The contact arnis G, G are nn'iunted upon insulating or insulated shafts J. .I' and at each end these shafts are provided with jointed levers K, K the lower ends of the levers K being pivoted or hinged to a block L mounted on a shaft L. This shaft L can be moved up and down by any mechanism such as is commonly used in oil-break electric switches and its motion causes the open in and closing of the contact arms G, G.

It is to be understood that the contactarms G, G need not necessarily be the only contacts of the switch; in switches for large loads other contacts may be used in conjunction with them such contacts being arranged to close after and open before the contact arms Gr, G which then act as arcing or sparking contacts.

lVhat I claim as my invention and desire to secure by Letters Patent is 1. In an oil break electric switch the combination with a tank adapted to contain insulating liquid, of a switch immersed in the liquid, a plurality of conductors entering the tank above the level of the switch and connected to the switch contacts and a single insulating member interposed between the switch and conductors in such manner as to completely protect the conductors from the vapors resulting from an are formed at the switch.

2. In an oil break electric switch the combination with atank adapted to contain insulating liquid, of a switch immersed in the liquid, conductors entering the tank from above the switch and connected to the contacts of said switch, and an insulating memll tl her in said tank interposed between the switch and conductors, said member extend ing below the switch and being disposed to protect the conductors from the vapors resulting from an are formed at the switch.

3. An oil break electric switch comprising in combination, a tank adapted to contain insulating liquid, said tank having a cover provided with a vent, movable electric switch contacts within said tank disposed below said vent whereby an unobstructed path is aiiorded for the vapors rising from the arc, and conductors entering the tank above the level of the insulating liquid extending to a point below the point of formation of the arc and connected to said contarts, each conductor within the tank having a portion extending parallel to the arc whereby the electro-magnetic force therein tends to elongate the arc and force it upward through the liquid.

4. An oil break electric switch comprising in combination, a tank adapted to contain insulating liquid, said tank having a cover provided with a vent, contacts in said tank located beneath said vent and positioned to form a horizontal arc when separated, conductors entering the tank above the level of the liquid and leading the current to and from the contacts, and a tubular insulating screen within the 1 tank, surrounding the contacts and serving to shield the conductors from the products of the arc.

5. In an oil-break electric switch the combination of a tank adapted to contain insulating liquid, contacts within said tank so disposed that the arc formed between them when circuit is broken is substantially horizontal, conductors leading the current to and from the contacts, and a tubular insulating screen within the tank and serving to shield the conductors from the products or the arc, said screen being so disposed as to cause the vapors oi the arc to set up a circulation in the insulating liquid in the tank.

6. In an oil-break electric switch the combination of a tank adapted to contain in sulating liquid, contacts within said tank so disposed that the are formed between them when circuit is broken is substantially horizontal, conductors leading the current to and from the contacts, a tubular insulating screen within the tank and serving to shield the conductors from the products of the arc and a free vertical vent for the vapors through the upper part of the tank above the contacts said vent forming a continuation of the tubular screen.

T. In an oil-break electric switch the combination of a tank adapted to contain insulating liquid, contacts within said tank so disposed that the arc formed between them when circuit is broken is substantially horizontal, conductors leading the current to and from the contact said conductors being so disposed relatively to the contacts and t0 the line of the are formed between them when circuit is broken that the electromagnetic forces tend to elongate the arc and force it upward through the oil, a tubular insulating screen within the tank and serving to shield the conductors from the products of the are, said screen being so disposed as to cause the vapors of the arc to set up a circulation in the insulating liquid in the tank, and a free vertical vent for the vapors through the upper part of the tank above said tubular screen and means for opening and closing the contacts.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

RICHARD WALTER GREGORY.

Witnesses:

JAMES VALTER HOGG, NORMAN THORNTON. 

